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Rare-earth Ions (rare-earth + ion)
Selected AbstractsStudy on Optical Properties of Rare-Earth Ions in Nanocrystalline Monoclinic SrAl2O4: Ln (Ln: Ce3+, Pr3+, Tb3+).CHEMINFORM, Issue 44 2005Zuoling Fu Abstract For Abstract see ChemInform Abstract in Full Text. [source] Anomalous concentration dependence of the coordination behavior of Cl, ion to Ln3+ ion (Ln3+ = rare-earth ion) in anhydrous LnCl3 alcohol solutionsJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2007Y. Yoshimura Abstract Raman spectroscopic measurements were carried out for the anhydrous LnCl3·20ROH·XLiCl solutions (Ln3+ = La3+, Lu3+, X = 0,3; ROH = MeOH, EtOH, n -PrOH) in the liquid state. The salt concentration (X) dependence of the wavenumber for the Ln,Cl stretching Raman band (,Ln,Cl) is examined in conjunction with the formation of chloro-rare-earth complexes. We have obtained very intriguing results including the fact that the chloro complexations of the middle rare-earth ions (e.g. gadolinium, holmium ions, etc.) in the MeOH and EtOH solutions show peculiar behavior with regard to the salt concentration dependence: the ,Ln,Cl wavenumber increases with the increasing chloride concentration. However, the ,Ln,Cl wavenumbers of the light and heavy rare-earth (e.g. lanthanum, lutetium, etc.) salt solutions show normal behavior; i.e. ,Ln,Cl decreases with the increasing chloride concentration. On the other hand, in the n -PrOH solutions, the ,Ln,Cl frequency in the solutions of all the rare-earth elements exhibits a normal behavior. We now present a possible mechanism for this anomalous concentration dependence of coordination of Cl, ions to Ln3+ ions in anhydrous LnCl3 alcohol solutions. Copyright © 2007 John Wiley & Sons, Ltd. [source] Deep level transient spectroscopy and TEM analysis of defects in Eu implanted GaNPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005A. Colder Abstract Deep level transient spectroscopy (DLTS) and transmission electron microscopy (TEM) are used to study europium implanted gallium nitride layers. The implantation was realised at room temperature in the random and channeled geometries. From DLTS, we determine intrinsic defects with associated levels located in the band gap (below the conduction band). Besides, we point out a new electron trap named Eu2. Its associated level is located at about Ec ,0.36 eV and the defect is probably related to the europium rare-earth ion. TEM investigation shows a difference in structure caused by changing the geometry of implantation. The random implanted sample contains numerous planar defects. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Purification, crystallization and X-ray diffraction analysis of a recombinant Fab that recognizes a human blood-group antigenACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2004Shuh-Chyung Song The NNA7 Fab fragment recognizes the human glycopeptide N blood-group antigen and has a high affinity for N-type glycophorin A (GPA). To provide insight into how antibodies recognize glycopeptide antigens, soluble Fab fragments were expressed in Escherichia coli, purified and crystallized using the hanging-drop vapor-diffusion method at 293,K. The best crystals were obtained from solutions of PEG monomethyl ether 5000 containing 4,8,mM yttrium chloride (YCl3). This rare-earth ion, which could be substituted with various lanthanides, changed the habit of crystals from multinucleated rods with a diffraction limit of 4.25,Å resolution to a diamond-shaped morphology that grew as single crystals and diffracted X-rays to 1.75,Å resolution. Data were collected that indicated that the crystals belonged to space group P212121, with unit-cell parameters a = 57.9, b = 77.1, c = 118.1,Å and one Fab fragment per asymmetric unit. A molecular-replacement solution has been obtained and 86% of the molecule was fitted by use of an automated refinement procedure (ARP). [source] Combined Optical and MR Bioimaging Using Rare Earth Ion Doped NaYF4 NanocrystalsADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Rajiv Kumar Abstract Here, novel nanoprobes for combined optical and magnetic resonance (MR) bioimaging are reported. Fluoride (NaYF4) nanocrystals (20,30,nm size) co-doped with the rare earth ions Gd3+ and Er3+/Yb3+/Eu3+ are synthesized and dispersed in water. An efficient up- and downconverted photoluminescence from the rare-earth ions (Er3+ and Yb3+ or Eu3+) doped into fluoride nanomatrix allows optical imaging modality for the nanoprobes. Upconversion nanophosphors (UCNPs) show nearly quadratic dependence of the photoluminescence intensity on the excitation light power, confirming a two-photon induced process and allowing two-photon imaging with UCNPs with low power continuous wave laser diodes due to the sequential nature of the two-photon process. Furthermore, both UCNPs and downconversion nanophosphors (DCNPs) are modified with biorecognition biomolecules such as anti-claudin-4 and anti-mesothelin, and show in vitro targeted delivery to cancer cells using confocal microscopy. The possibility of using nanoprobes for optical imaging in vivo is also demonstrated. It is also shown that Gd3+ co-doped within the nanophosphors imparts strong T1 (Spin-lattice relaxation time) and T2 (spin-spin relaxation time) for high contrast MR imaging. Thus, nanoprobes based on fluoride nanophosphors doped with rare earth ions are shown to provide the dual modality of optical and magnetic resonance imaging. [source] Efficient Luminescence from Rare-Earth Fluoride Nanoparticles with Optically Functional Shells,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2006M. Lezhnina Abstract Rare-earth fluorides are a class of materials with considerable potential in optical applications. Fluoride lattices typically permit high coordination numbers for the hosted rare-earth ions, and the high ionicity of the rare-earth-to-fluorine bond leads to a wide bandgap and very low vibrational energies. These factors make rare-earth fluorides very useful in optical applications employing vacuum ultraviolet and near-infrared excitation. The preparation of nanometer-sized particles has opened the door for new properties and devices if the performance of their macroscopic counterparts can be conserved in the nanometer regime. However, at small particle sizes, defect surface states and adhering water reduce the optical efficiency. These shortcomings can be reduced by applying protective shells around the luminescent cores, which can also be involved in the luminescent process. [source] Fluorescence spectra of Pr3+ ions in phosphate materials calculated by the DVME methodINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 12 2009Y. Kowada Abstract Recently, fluorescence spectra of rare-earth ions in oxide materials are very attractive for the applications of the optical amplification in optical fiber communications, white LED, etc. However, it has been difficult to calculate the fluorescence spectra of rare-earth ions by the first principle method. In this study, we used the relativistic discrete-variational multielectron (DVME) method, which is a configuration-interaction (CI) calculation program using the molecular orbitals obtained by the relativistic DV-X, method. We applied this method for the calculation of the fluorescence spectrum of the Pr3+ ions in phosphate materials. The transition probability of the fluorescence was calculated in the same manner of the absorption. The obtained theoretical fluorescence spectrum was in good agreement with the experimental one, though the intensity of each peak was deeply dependent on the configuration of the surrounding structural units. The results suggested that the DVME method was useful for the calculation of not only absorption but also fluorescence spectra of rare-earth ions in oxide materials. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Effects of magnetic field and rare-earth ions on properties of polyaniline nanoparticlesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Shuling Zhang Abstract The uniform polyaniline nanoparticles with the size of about 50 nm were electropolymerized using the method of constant potential of 0.8 V. The effects of rare-earth cations and magnetic field on the preparation and properties of polyaniline were investigated. It was found that the addition of rare-earth cations could enhance the effect of magnetic field on the properties of polyaniline. The resulting products were characterized by FTIR spectra, UV,vis spectra and scanning electron microscope (SEM); the conductivity and cyclic voltammetry (CV) were also investigated. The experimental results show that the magnetic field has an orientation effect on polyaniline chain and there exists the interaction between rare-earth cations and polyaniline chain because of the electrostatic interaction. The addition of rare-earth cations can increase electrical conductivity, moreover, the effect of NdCl3 and ErCl3 on properties of polyaniline is more remarkable than LaCl3 and SmCl3. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2286,2294, 2007 [source] Anomalous concentration dependence of the coordination behavior of Cl, ion to Ln3+ ion (Ln3+ = rare-earth ion) in anhydrous LnCl3 alcohol solutionsJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2007Y. Yoshimura Abstract Raman spectroscopic measurements were carried out for the anhydrous LnCl3·20ROH·XLiCl solutions (Ln3+ = La3+, Lu3+, X = 0,3; ROH = MeOH, EtOH, n -PrOH) in the liquid state. The salt concentration (X) dependence of the wavenumber for the Ln,Cl stretching Raman band (,Ln,Cl) is examined in conjunction with the formation of chloro-rare-earth complexes. We have obtained very intriguing results including the fact that the chloro complexations of the middle rare-earth ions (e.g. gadolinium, holmium ions, etc.) in the MeOH and EtOH solutions show peculiar behavior with regard to the salt concentration dependence: the ,Ln,Cl wavenumber increases with the increasing chloride concentration. However, the ,Ln,Cl wavenumbers of the light and heavy rare-earth (e.g. lanthanum, lutetium, etc.) salt solutions show normal behavior; i.e. ,Ln,Cl decreases with the increasing chloride concentration. On the other hand, in the n -PrOH solutions, the ,Ln,Cl frequency in the solutions of all the rare-earth elements exhibits a normal behavior. We now present a possible mechanism for this anomalous concentration dependence of coordination of Cl, ions to Ln3+ ions in anhydrous LnCl3 alcohol solutions. Copyright © 2007 John Wiley & Sons, Ltd. [source] Calculation of rare-earth 4d giant-absorption spectra with multiplet effects and decay processesJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001Haruhiko Ogasawara The total and partial photoelectron yield spectra of all the trivalent rare-earth ions in the 4d giant resonance region are calculated with full multiplet effects. The decay processes are treated as coherent processes following photoexcitation. The results reproduce the over all features of experiments. It is obtained that the character of the giant-absorption is different between the light and heavy rare-earths. The multiplet effects play an essential role in the decay processes. [source] Room-Temperature Solid-State Reaction Behavior, Hydrothermal Crystallization and Physical Characterization of NaRE(MoO4)2, and Na5Lu(MoO4)4 CompoundsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2010Jianhua Wu In the context, a novel composite synthesis technology is engaged in the preparation of NaRE(MoO4)2 (RE=Y, La, Nd, Eu, Gd, Tb, Er, and Yb) and Na5Lu(MoO4)4 compounds, which involves a room-temperature solid-state reaction and hydrothermal crystallization process. The synthesis mechanism is predicted, indicating that higher temperature and moisture can speed up the reaction process and especially the existence of crystalline water molecules in the precursor is necessary for the solid-state reaction at room temperature. It is found that different rare-earth nitrate precursors present different reactivity to sodium molybdate at room temperature. The crystallization degree of the products after the room-temperature solid-state reaction depends on the melting point of rare-earth nitrate precursors. The hydrothermal treatment is beneficial for the good crystallization of NaRE(MoO4)2 (RE=Y, La, Nd, Eu, Gd, Tb, Er, and Yb) and Na5Lu(MoO4)4. Finally, the photoluminescent spectra for these NaRE(MoO4)2:Eu3+ (La, Gd, and Y) are studied, which depend on the species of rare-earth ions. [source] Facile fabrication of novel Eu-containing copolymer and luminescent propertiesPOLYMER ENGINEERING & SCIENCE, Issue 7 2009Ziqun Huang A new Eu-containing copolymer was successfully fabricated through two steps. First, the Eu-containing monomer was synthesized from 4-Vinylbenzoic acid and europium ion (Eu3+) complex, which rare-earth ions connect with the ligand by covalent bands. Next, the copolymer was obtained by free-radical copolymerization of Eu-containing monomer with methyl methacrylate using 2, 2,-azobis(isobutyronitrile) (AIBN) as initiator at low temperature. Infrared spectroscopy, gel permeation chromatography and scanning electron microscopy were applied to characterize the structure of the polymer. UV-visible absorption/photoluminescence spectra and fluorescence spectra were taken to valuate the photophysical properties of the obtained Eu-containing copolymer. The experimental result shows that the strong luminescence of europium ions substantiates optimum energy match and effective intramolecular energy transfer between the triplet state energy of coordination complex and the emissive energy level of the rare-earth ions. A study of the dependence of emission intensities of the Eu-containing nanoparticles on the Eu content showed that the emission intensities increased nearly linearly with increasing Eu content. In addition, no significant emission concentration quenching phenomenon was observed at the Eu content of 0,4.61 mol%. The hybrid material systems can be expected to have potential applications in light conversion materials. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] Organic,inorganic hybrid mesoporous silicas: functionalization, pore size, and morphology controlTHE CHEMICAL RECORD, Issue 1 2006Sung Soo Park Abstract Topological design of mesoporous silica materials, pore architecture, pore size, and morphology are currently major issues in areas such as catalytic conversion of bulky molecules, adsorption, host,guest chemistry, etc. In this sense, we discuss the pore size-controlled mesostructure, framework functionalization, and morphology control of organic,inorganic hybrid mesoporous silicas by which we can improve the applicability of mesoporous materials. First, we explain that the sizes of hexagonal- and cubic-type pores in organic,inorganic hybrid mesoporous silicas are well controlled from 24.3 to 98.0,Å by the direct micelle-control method using an organosilica precursor and surfactants with different alkyl chain lengths or triblock copolymers as templates and swelling agents incorporated in the formed micelles. Second, we describe that organic,inorganic hybrid mesoporous materials with various functional groups form various external morphologies such as rod, cauliflower, film, rope, spheroid, monolith, and fiber shapes. Third, we discuss that transition metals (Ti and Ru) and rare-earth ions (Eu3+ and Tb3+) are used to modify organic,inorganic hybrid mesoporous silica materials. Such hybrid mesoporous silica materials are expected to be applied as excellent catalysts for organic reactions, photocatalysis, optical devices, etc. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 32,42; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20070 [source] | |||||||||||||